Dynamo-machine.



No. 743,082. PATENTED NOV. 3, 1903. D. G. JACKSON.

DYNAMO MACHINE.

APPLI OATION FILED AUG.11, 1902.

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- DYNAMO MACHINE.

APPLICATION FILED AUG.11, 1902.

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' W @W% W Attorneys Patented November 3, 1203.

PATENT OFFICE.

DUGALD O. JACKSON, OF MADISON, VISCONSIN.

DYNAMO-MACHINE.

SPECIFICATION forming part of Letters Patent No. 743,082, dated November3, 1903.

Application filed August 11, 1902. Serial No,l19,Z69. (No model.)

To all whom it may concern.-

Be it known that I, DUGALD O. JACKSON, a citizen of the United States,residing at Madison, in the county of Dane and State of Wisconsin, haveinvented a certain new and useful Improvement in Dynamo-Machines, ofwhich the following is a full, clear, concise, and exact description,reference being had to the accompanying drawings, forming a part of thisspecification.

My invention relates to dynamo-machines, and has for its object theprovision of means whereby sparking at the brushes may be avoidedwithout resorting to the usual alternative of shifting the brushes.

More particularly my invention relates to the excitation of thefield-magnets of dyna mo-machines having coinmutators in such a way thatthe lines of magnetic force will always thread through the armature withan approximately constant fixed direction and strength without regard tovariations of current in the armature-coils or to the direction ofrotation of the armature. By thus maintaining a constant direction andstrength of the magnetic field it is unnecessary to shift the positionof the brushes under varying conditions of current, pressure, or speed,and while the brushes remain in but one position sparking at thecommutator is almost entirely avoided.

As is well understood by those skilled in the art, it is necessary in amotor or generator in order to prevent sparking to maintain apractically constant angle between the diameter of commutation and thedirection of the lines of force through the armature. If thefield-magnets of a dynamo-machine are excited by the customaryfield-windings, lines of force flow between the pole-pieces in a certaindirection. If now an electric circuit be closed through the rotatingarmature, electric currents will be set up in the armature-conductors,which currents in turn will cause lines of magnetic force to flow abouteach conductor. Some of the armature-conductors will have a positionsuch that the lines of force they set up will fiow in a direction moreor less at right angles with the path of the lines of force set up bythe field-magnets. The conductors which set up these lines of force atright angles to the normal field are commonly known as cross-turns. Theresult is that instead of having a magnetic field due to themagnetization of the field polep'ieces alone there is a resultant field,whose direction is determined by the relative strength of the magneticfield due to the armature cross turns as compared with the strength ofthe magnetic field caused by the field-magnets, and as the currentvaries in the armature cross-turns the strength of the correspondingmagnetic field will vary, thus causing a variation in the direction andstrength of the resultant magnetic field threading the armature, and tomaintain a constant angle between the direction of this resultant fieldand thediameterofthe commut-ationitis apparent that as the direction ofthe field varies, due to variations of current in the armaturecrossturns, the direction of the diameter of commutation will also haveto be changed. This changing of the position of the brushes is anobjectionable feature in the regulation of dynamo-machines, whether itbe accomplished by hand or by more or less automatic means. It hastherefore been proposed to magnetically neutralize the effect of thearmature crossturns by associating with each armatureconductor aparallel conductor stationarily mounted outside, but near to theperiphery of the armature, in which neutralizing-conductor equalelectric currents flow, but in opposite directions to the currents inthe armature-conductors. Theproposed embodiments of this idea havecontemplated an iron fieldmagnet made in the form of a ring whichentirely surrounds the armature and about which the neutralizing orcompensating conductors are wound,as on a Gram me-ring armature. Thisisan expensive construction and an undesirable form of field-magnet.Other embodiments of this idea have been unsuccessful because ofincomplete compensation of the cross-turns or because the compensatingconductors have not been properly placed with reference to thearmature-conductors, and, furthermore, the winding of the compensatingconductors has heretofore been unduly expensive and they have beendifficult to properly insulate.

My invention contemplates an improved method of winding compensatingconductors, whereby every armature-conductor will be paralleled by acompensating conductor disposed with corresponding angularity about thearmature-axis. The compensating winding is thus electrically identicalwith the armature-winding, except that the currents flow in onedirection in an armature-conductor and in the opposite direction in theadjacent compensating conductor. In order to accomplish this perfectcompensation at a small cost and at the same time to retain the presenteiiicient form of field-magnets, I preferably provide bridges insertedbetween poletips. These bridges are preferably of nonmagnetic and may beof non'conducting material; but they may be made of iron under someconditions. The compensating conductors are preferably laid inuniformlyspaced slots formed in the pole-faces and in the bridgessimilar to the slots within which the armature-conductors are laid. Itwill be seen that these slots may be very readily made in the pole-faceswhen the latter are made up of laminated iron punchings, as is nowadaysfrequently done. In this case it is evident that the slots may bepunched in the pole-face punchings in a manner which is analogous to theWay in which the slots are punched in the armature-punchings.

It is a well-known practice among those skilled in the art to windarmature-coils on formers and then place them in the slots after thecoils and slots have been duly insulated. The armature-coils are allalike. It is characteristic of the construction of my invention that allthe compensation-coils are alike and that they may be wound up onformers and applied to the slots when the machine is assembled.Compensation-coils can thus be independently insulated, following themanner of insulating the armature-coils.

My invention will be best understood by reference to the accompanyingdrawings, in which 1 Figure 1 is a diagrammatic illustration of thearmature and compensation-coil windings and connections. Fig. 2 is anend elevation of a dynamo-machine equipped with my improvedcompensation-coils. Fig. 3 is a perspective view of a singlecompensation-coil as wound upon a former.

Like reference characters refer to like parts in the various figures.

I preferably provide the usual field-frame 1, within which are mountedpole-pieces 2. The rotatable armature-core 3 is supported by bearings 4and provided with a commutator 5. Brushes 6 6 are adapted to conductcurrent to and from the commutator. The spaces between the pole-piecesare filled in by the bridges 7 7, preferably of non-magnetic material.

For purposes of illustration I have shown the compensation-coilsarranged to compensate the armature reactions for an armature whichcarries forty conductors and which is arranged to operate in a four-polefield and which has four ducting-paths through its windings. Thearmature-coils are laid in slots 8 8 of the armature-core and are heldin place by the wedges 9 9, preferably made of wood or other insulatingmaterial. In a similar manner the coils of the compensationwindings arelaid in the uniformly-spaced slots 10 10, cut in the pole faces andbridges, where they are held in place by the wedges 11 11.

Each'of the conductors 12 and 13 (shown upon the diagram of Fig. 1) maybe considered to represent either a single conductor or thecross-section of a coil, the several coils being connected together inthe manner illustrated by the end connections. The front connections arerepresented by the heavy lines, while the back connections arerepresented by the lighter lines.

In the drawings I have shown a four-path armature and have also shownthe compensation-coils divided into four parallel paths. It is notessential, however, that the compensation-coils shall have the samenumber of parallel paths as the armature-coils, provided when exactcompensation is required that the number of paths and conductors are sorelated to each other that the product of the number of conductors withthe amperes carried by each is equal to the corresponding product of thenumber of armature-conductors with the amperes carried by each.

On some occasions it may be desired to somewhat overcompensate orsomewhat undercompensate, and, again, it may be desired to alter thecompensation. In this case the number of compensating conductors may bemade different from the number required to cause the compensating ampereturns to equal the armature ampere-turns. The compensating ampere-turns,for instance, might be made larger than the armature ampereturns if allthe current flowing through the armature were permitted to flow throughthe compensating conductors, and a shunt resistance may be placedbetween the terminals of the compensating windings, so that any desiredportion of the armature-current will flow through the compensatingwindings. This shunt may be either a fixed shunt or a variable one. Inthe present embodiment of my invention I have shown such a variableshunt resistance at 14. The plus and minus terminals of the machine areshown at 15 and 16, the direction of current in the connectingconductorsbeing shown by the arrows. The shunt-field-excitation winding isdiagrammatically represented at 17, it being connected to the terminals15 and 16.

In Fig. 3 I have shown a coil 18, having terminals 19 and 20, and whichis adapted to be laid in slots for the compensating winding. It will beapparent that as the coils are uniformly spaced they are all alike andmay be wound on the same former.

The construction illustrated is equally adapted for use on generators ormotors; but it is particularly advantageous for use with motors whichare desired to be operated at difierent times at widely-differingspeeds. With the compensation for armature reactions here described thespeed of the motor may be altered by varying the shunt-field eX-citation through a wide range without producing sparking at the brusheson the commutator.

It will be seen that my invention has, among others, a particularadvantage as compared with the prior art in that it permits the use ofindependently-wound coils, (when this is desired,) which may be appliedto the polepieces in a manner that is entirely similar to the manner ofapplying independently-Wound coils to the armature-core. It also has,among others, the advantage of being applicable to ordinary types ofdynamos.

In this specification and these claims the term dynamo is used to meaneither a generator or a motor, as commonly understood in ordinaryelectrical parlance.

While I have shown and particularly described one embodiment of myinvention, it is evident that many modifications and changes might beadvantageously made without departing from the spirit thereof, and I donot, therefore, Wish to limit myself to the precise disclosure astherein set forth; but,

Having described my invention, I claim as new and desire to secure byLetters Patent 1. In a dynamo, the combination with a field-magnethaving salient pole-pieces, of an armature, slots formed in thepole-faces, and a compensation-winding laid in said slots, saidcompensation-winding being composed of previously-formed coils,substantially as described.

2. In a dynamo, the combination with a field-magnet having salientpole-pieces, of an armature, equally-spaced slots formed in thepole-faces, and a compensation-winding laid in said slots, saidcompensation-winding being composed of previously-formed coils,substantially as described.

3. In a dynamo, the combination with a field-magnet having salientpole-pieces, of an armature, and a compensation-Winding distributedabout said armature at the polefaces, said compensation-winding beingcomposed of previously-formed coils, substantially as described.

4. In a dynamo, the combination with a field-magnet having salientpole-pieces, of an armature, bridge-pieces between said polepieces,slots formed in the faces of said pole and bridge pieces, and acompensation-winding laid in said slots, said compensation-Winding beingcomposed of previously-formed coils, substantially as described.

5. In a dynamo, the combination with a field-magnet having salientpole-pieces, of an armature, bridge-pieces between said polepieces,equally-spaced slots formed in the faces of said pole and bridge pieces,and a compensation-winding laid in said slots, said compensation-winding being composed of previously-formed coils,substantially as described.

6. In a dynamo, the combination with a field-magnet having salient polepieces, of an armature, bridge-pieces between said polepieces, slotsformed in the faces of said pole and bridge pieces, acompensation-Winding laid in said slots, said compensation-winding beingcomposed of previously-formed coils, and adjustable means forcontrolling the cur rent-flow through the compensation-windin g,substantially as described.

7. In a dynamo, the combination with a field-magnet having salientpole-pieces, of an armature, bridge-pieces between said polepieces,equally-spaced slots formed in the faces of said pole and bridge pieces,a compensation- Winding laid in said slots, said compensation windingbeing composed of previously formed coils, and adjustable means forcontrolling thecurrent-fiow through the compensation-winding,substantially as described.

8. In a dynamo, the combination with a field-magnet having salientpole-pieces, of an armature, a compensation-winding distributed aboutsaid armature at the pole-pieces, said compensation-winding beingcomposed of previously-formed coils, and adjustable means forcontrolling the current-flow through the compensation-winding and thearmature, substantially as described.

In witness whereof I hereunto subscribe my name this 28th day of July,A. D. 1902.

DUGALD C. JACKSON.

Witnesses:

GEORGE L. Calico, HARVEY L. HANSON.

